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arXiv · 1710.00111

Broadband near-infrared antireflection coatings fabricated by three dimensional direct laser writing

Y. Li·D. B. Fullager·E. Angelbello·D. Childers·G. Boreman·T. Hofmann
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Abstract

Three-dimensional direct laser writing via two photon polymerization is used to fabricate anti-reflective structured surfaces composed of sub-wavelength conicoid features optimized to operate over a wide bandwidth in the near-infrared range from 3700 cm$^{-1}$ to 6600 cm$^{-1}$ (2.7 to 1.52 $μ$m). Analytic Bruggemann effective medium calculations are used to predict nominal geometric parameters such as the fill factor of the constitutive conicoid features of the anti-reflective structured surfaces presented here. The performance of the anti-reflective structured surfaces was investigated experimentally using infrared transmission measurements. An enhancement of the transmittance by 1.35\% to 2.14\% over a broadband spectral range from 3700 cm$ ^{-1} $ to 6600 cm$^{-1}$ (2.7 to 1.52 $μ$m) was achieved. We further report on finite-element-based reflection and transmission data using three-dimensional model geometries for comparison. A good agreement between experimental results and the finite-element-based numerical analysis is observed once as-fabricated deviations from the nominal conicoid forms are included in the model. Three-dimensional direct laser writing is demonstrated here as an efficient method for the fabrication and optimization of anti-reflective structured surfaces designed for the infrared spectral range.

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Y. Li, D. B. Fullager, E. Angelbello, D. Childers, G. Boreman, T. Hofmann. 2017-09-29. Broadband near-infrared antireflection coatings fabricated by three dimensional direct laser writing. https://doi.org/10.1364/ol.43.000239

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